Items for this newsletter should be emailed to the editor: asgrg *AT* hotmail *DOT* com

Subscriptions should be sent to the Treasurer: Dr Susan M. Scott, Dept of Physics & Theoretical Physics, The Faculties, Australian National University, Canberra ACT 0200, Australia.

Receipts will be issued. Email enquiries to Susan.Scott@anu.edu.au

The *closing date for entries has been
to August 31, 1996* and a
decision on the winner should be made by the end of September 1996.
Furthermore, although the specifications below are preferred, entries will now
be accepted in any format, including a hand drawing (to be redrawn in
postscript later).

All entries should be sent to David Wiltshire, Department of Physics and Mathematical Physics, University of Adelaide, SA 5005, Australia.)

If using email please try to send it as either as a
postscript file (preferably *encapuslated postscript*) or a
TeX/LaTeX/Metafont file. While colour entries will be accepted, the
logo should look good in black and white, as it is intended that it be included
in letterheads produced by TeX/LaTeX, and most people do not routinely use
colour printers for letters! The entries will be sent on to the judging panel
with the entrant's name *kept anonymous *(until a decision
has been reached). Joint entries up to a maximum of 3 collaborants will be
accepted, and there is no limit to the number of entries submitted by any
person(s). The prizes are as follows:

Single entrant Life membership of ASGRG

2 joint entrants 5 years free membership each

3 joint entrants 3 years free membership each

ASGRG President Peter Szekeres has written to the Chair of the ARC, Prof. Max Brennan, to inform him of our existence and to request that a category code for "General Relativity, Gravitation and Cosmology" be established. In presenting our case Dr Szekeres not only mentioned the well-defined nature of GR, as evidenced by the 5 international journals devoted to the field, but also presented statistics on Australian subscription to the electronic archives at Los Alamos and MSRI, which shows active interest in gr-qc in Australia. Readers may be interested in the statistics, compiled on 27/2/96:

ARCHIVE | DESCRIPTION | Date | N(world) | N(Oz) | %(Oz) |
---|---|---|---|---|---|

started | |||||

hep-th | High Energy Physics Theory | 8/91 | 2711 | 54 | 2.0 |

hep-lat | High Energy Physics Lattice | 2/92 | 1077 | 16 | 1.5 |

alg-geom | Algebraic Geometry | 2/92 | 1427 | 11 | 0.8 |

hep-ph | HEP Phenomenology | 3/92 | 2622 | 30 | 1.1 |

astro-ph | Astrophysics | 4/92 | 2726 | 48 | 1.8 |

cond-mat | Condensed Matter | 4/92 | 2937 | 33 | 1.1 |

funct-an | Functional Analysis | 4/92 | 230 | 6 | 2.6 |

gr-qc | General Relativity & Qu. Cosmology | 7/92 | 1608 | 42 | 2.6 |

nucl-th | Nuclear Physics -- Theory | 10/92 | 919 | 18 | 2.0 |

dg-ga | Diff Geometry & Global Analysis | 6/94 | 820 | 12 | 1.5 |

chem-ph | Chemical Physics | 3/94 | 577 | 9 | 1.6 |

supr-con | Superconductivity | 11/94 | 342 | 3 | 0.9 |

nucl-ex | Nuclear Experiment | 11/94 | 206 | 3 | 1.5 |

quant-ph | Quantum Physics | 11/94 | 751 | 20 | 2.7 |

plasm-ph | Plasma Physics | 9/95 | 30 | 0 | 0.0 |

atom-ph | Atomic, Molecular & Optical Physics | 9/95 | 152 | 6 | 3.9 |

**N(world)**=number of subscribers worldwide (on 27/2/96)

**N(Oz)**=number of subscribers in Australia (on 27/2/96) at an academic
site (ending in "edu.au", "oz.au"), government (CSIRO) site ("gov.au"),
or an industry site ("com.au").

**%(Oz)**=Australian participation as percentage of world total. Although
these percentages measure consumption rather than production, they are all
roughly consistent with previous ARC findings that Australia produces about 2%
of world scientific research.

Most notably, general relativity is now the domain of ever more precise experimental tests, and the challenges provided by the possibility of direct detection of gravitational waves have made general relativity a testing bed for some of the most advanced technologies available today. The sensitivities required for detecting gravity waves are driving new standards in lasers, timing devices, suspensions etc. David McClelland (ANU) opened the conference with a overview of the technical issues involved in detection of gravitational waves, and the plans for building a detector in Australia to be part of the international gravitational wave observatory. Such an initiative will be extremely exciting; it will open a new window on the universe with the potential to provide many undreamed of astronomical discoveries. The lessons we have learnt from just probing new windows in the electromagnetic spectrum demonstrate that the universe is a highly dynamic environment full of phenomena which were entirely unexpected. The possibility of "seeing" with an entirely different physical interaction could therefore have breathtaking consequences. We know for certain that we will learn much about the dynamics of objects such as black holes, and quite possibly the mysteries of the phenomena that power active galaxies and quasars, and beyond that is anyone's guess. Since several widely separated detectors are needed around the globe in order to make gravitational astronomy a reality, Australia has an important part to play in this endeavour. Although there will be some cost involved, the feedback in terms of the prestige for Australian science in being an integral part of such a major international undertaking would be immense, and we need to convince our colleagues and politicians that this is something we need to get behind now rather than missing the boat and belatedly trying to catch up some years down the track. David McClelland described how with a bit of ingenuity it would be possible to come up with an effective GW detector on a realistic Australian budget. Alex Abramovici (Caltech) presented a plenary talk on the status of the LIGO long baseline laser interferometric GW detector, and on problems being addressed using the 40m prototype at Caltech. He noted that the construction of a GW detector in Australia was important if the international network of detectors was to be fully exploited, and encouraged his Australian colleagues to persevere with their efforts to build a detector. David Blair (UWA) described how the stochastic background of gravitational waves from cosmological supernovae could provide an alternative source of waves observable by cross-correlation of suitably spaced detectors.

Technical details associated with the development of laser interferometric and resonant bar gravitational wave detectors were discussed in a set of Experimental Workshops. John Sandeman opened the workshop with a review of the activities of the Australian Consortium for Interferometric Gravitational Astronomy (ACIGA) over the previous 12 months. ACIGA is a consortium formed by ANU, Adelaide and UWA to investigate technology required for second generation long baseline laser interferometric detectors. David Ottaway and Damien Mudge (Adelaide) talked about the development of an efficient, stable, high power laser. Charles Harb and Eleanor Huntington (ANU) talked about a quantum mechanical model for injection locking of lasers and about the practicalities. David McClelland (ANU) reported on experiments to test advanced interferometry techniques (recycling). Mark Nottcut (UWA) talked about frequency stabilisation of a laser using a cryogenic Fabry Perot reference cavity. Ju Li (UWA) gave two talks, one on vibration isolation systems and another on the use of sapphire test-mass mirrors in laser interferometric detectors. Chris Walsh (CSIRO-DAP) reported on their progress in fabrication of mirrors for gravitational wave detectors. Alex Tikhomirov (Adelaide) discussed an experiment in which aberrations in an interferometer had been removed using a holographic beam-splitter as an example of how diffractive optics could be used to advantage in interferometers. Finally, Eugene Ivanov reported on the status and future prospects for the UWA resonant-mass gravitational wave detector. The experimental workshops concluded with a discussion lead by Alex Abramovici (LIGO group) on the outstanding problems for laser interferometers, and a presentation by consortium members of their plans for 1996. The workshops were greatly enhanced by the presence of Alex Abramovici and Ingo Freitag from the Lazer Zentrum in Hannover, who asked many questions and provided useful feedback.

The conference not only heard about the technical issues involved in gravitational wave detection but also about the mathematical issues involved in determination of gravitational wave signatures through the modeling of phenomena such as the inspiral of neutron stars. In such situations numerical modeling is necessary and groups at New England and Monash are working on different approaches to the problem. Robert Bartnik and Andrew Norton discussed an approach based on a null quasi-spherical coordinate gauge. This approach facilitates the use of fast Fourier transforms and spectral representations. The advantages of spectral techniques which have long been exploited in meteorology, but little in the numerical relativity community, were also emphasised by Daniel Prager of Monash in his discussion of work on the Robinson-Trautman spacetime. Tony Lun presented the characterisation of radiating spacetimes in general, including the radiative reaction which is ignored in linearised computations, and both he and Ernie Chow discussed the Robinson-Trautman spacetime as a radiative exact solution in which features such as the amount of energy, momentum and angular momentum transported can be identified. Other numerical approaches being investigated by the Monash group were also presented: Joe Monaghan gave a paper on smoothed particle hydrodynamics, which builds on a post Newtonian formulation of fluid dynamics due to Chandrasekar, and which proves to be particularly flexible and robust for discussing mildly relativistic binary systems. Leo Brewin and Adrian Gentle discussed aspects of Regge calculus, and the problem of truncation errors in particular. Brewin also presented an alternative to the Regge calculus, which he argued was better suited to numerical relativity than the traditional Regge approach. Finally, Clifford Will (Washington Univ., St.~Louis), described recent developments on extending the post-Newtonian approximation to orders of (v/c)^2 sufficiently high for extracting information such as the mass and spin of bodies in binary systems from their gravitational wave signals.

In addition to gravitational waves, many different theoretical aspects of relativity and gravitation were discussed. On the mathematical side Sue Scott (ANU) described the definition of geometrical "abstract boundary" which she has developed with Peter Szekeres as a tool for discussing singularities of manifolds, while Szekeres outlined the present status of cosmological singularity theory and suggested how a generalised "Hubble index" might be a useful tool in their analysis. Ben Evans (ANU) discussed in detail some properties of the Curzon solution. The problem of analysis of the singularity structure of cusps on cosmic strings was discussed by Malcolm Anderson (Edith Cowan), who demonstrated that earlier objections of Geroch and Traschen to the definition of strings in terms of metrics with a distributional curvature may be overcome. A modified Newman-Penrose formalism was described by Joe Fernandes (Monash) in application to treating gravitational perturbations in a gauge- invariant fashion in a Kerr background. The mathematical characterisation of inflationary dynamics in scalar field cosmologies was addressed by Scott Foster (Adelaide). John Carminati (Deakin) described the progress he had made towards solving an as yet unsettled problem of George Ellis on shear-free dust cosmologies. Peter Waylen (Canterbury) showed how it was possible to generate exact time-dependent axi-symmetric solutions of Einstein's vacuum equations. Dmitri Gal'tsov (Moscow State) showed how the solution-generating techniques of Ehlers, Harrison et al. may be generalised from general relativity to stringy gravity models incorporating the dilaton and axion fields. Philip Charlton (Newcastle) discussed the properties of the massless Dirac equation in algebraically spacetimes. Ted Fackerell (Sydney) did an admirable job of debunking Yilmaz et al., who have appeared to seriously misunderstand general relativity and to have their misunderstanding published.

A variety of approaches to the problems of quantum gravity were presented. Paul Davies (Adelaide) and David Tilbrook (Macquarie) discussed the problems of accelerated and rotating particle detectors in the framework of quantum fields in curved spacetime. The loop approach of Ashtekar et al. was enthusiastically advocated in talks by Elizabeth Wood (Monash) and Chuen Toh (ANU). Michael Kuchiev (UNSW) presented his own alternative for quantum gravity as a gauge theory in flat spacetime, in which gravitational effects arise through the "polarisation of instantons". Reg Cahill (Flinders) discussed conceptual issues involved in quantum gravity and emphasised the need to regard the problem as one of deriving the classical spacetime from the quantum one -- "classicalisation" rather than quantisation. The problem of quantum decoherence was also addressed by Andrew Matacz (Sydney) in the framework of stochastic inflation in cosmology. He demonstrated how the Feynman-Vernon influence functional method can be adapted as a useful tool for describing the evolution of density perturbations in the early universe. Bob Geroch (Chicago) gave a an elegant talk on the mathematical problems associated with the definition of path integrals and the problem of constructing a measure on the space of all paths. Hugh Luckock (Sydney) described the advances that have been made in quantum cosmology recently through the incorporation of supersymmetry. Rafael Sorkin (Syracuse) discussed quantum fluctuations in the shape of the horizon of stationary black holes, and concluded that heuristically they exhibit a fractal character, with order lambda fluctuations occurring on all scales lambda below M^{1/3} in natural units. Finally, Jim McCarthy discussed 2-dimensional models of black hole evaporation which have aroused great interest over the last few years as toy models in which the back-reaction on the spacetime geometry can be fully treated at the semiclassical level.

In addition to the scientific programme, Clifford Will also presented a very polished public lecture entitled "Was Einstein right?", a reminder of the extraordinary experimental success of general relativity. It was very disappointing to note that the popular press was at the same time giving much greater coverage to the claims of an overseas oddball that Einstein was wrong.

The social programme was also a great success, culminating in a day trip to the Currency Creek winery near Goolwa, and a swim at Port Elliot in perfect conditions. All participants seemed to agree that the conference was a tremendous success, and we encourage all of you who did not make it to come to ACGRG2 in Sydney in July, 1998.

**NEWS SNIPPETS** ... for those who missed this one,
perhaps gravity waves from neutron star mergers are a lot more powerful than
hitherto suspected. For further details see gr-qc/9601017.

From New Scientist (20 Jan 96)

Huge instruments are being built in the US and Italy to pick up the as yet undetected ripples in the fabric of space-time called gravitational waves. The most common source of these waves was thought to be the merger of dense neutron stars, which are left behind when a star explodes into a supernova. But two American physicists now claim that these mergers hardly ever occur. They say that astronomers should look for gravitational waves caused by merging black holes. "We have found that when neutron stars spiral together they very likely change into black holes just before they coalesce," says Grant Mathews of the University of Notre Dame in Indiana.

"The good news is that merging black holes probably produce a stronger burst of gravitational waves than merging neutron stars," says Mathews. "The bad news is that nobody knows the gravity wave signature of such an event."

Mathews and James Wilson of the Lawrence Livermore National Laboratory in California simulated what happens to two neutron stars, each 20 kilometres in diameter, as they spiral together. "In the past, theorists have simplified the situation by assuming the gravity experienced by each star is approximated by Newtonian gravity plus a `perturbation'," says Mathews. "However, the forces near each star are so strong that only Einstein's theory of gravity -- general relativity -- adequately describes what goes on."

When Mathews and Wilson applied general relativity they were amazed by what happened to the two stars between 1 and 4 seconds before the merger when they were orbiting each other once every few milliseconds and their centres were only 40 kilometres apart. "Space became enormously warped around the two stars and their orbital velocity -- about a quarter of the speed of light -- boosted their masses," says Mathews. "The net effect was to increase the effective gravity at the surface of each star." The increase was only about 10 per cent, but it was enough to crush each star into a black hole (Physical Review Letters, vol 75, p 4161). The two black holes then merged.

If Wilson and Mathews are right, only a tiny minority of neutron stars -- those that are relatively light -- ever coalesce without first becoming black holes. Unfortunately, the physics of black hole mergers remains one of the great unsolved mysteries of general relativity, so theorists will have their work cut out predicting the gravitational wave signature of such an event.

But astronomers can take heart from the fact that when two black holes merge they are closer together than two neutron stars and will therefore experience fiercer mutual gravity. This should result in a more powerful burst of gravitational waves as the stars merge.

Wilson and Mathews add that the gravitational wave signal from two neutron stars may change abruptly at the instant when they transform into two black holes. "This may give rise to a new and unexpected signal to look for," says Mathews.

The sudden formation of two black holes by a pair of neutron stars spiralling in towards one another might even help to explain a long-standing astronomical puzzle: the source of mysterious bursts of gamma rays. A burst of gamma rays erupts somewhere in the sky about once a day. "When the two black holes form, there may be heating, jets, neutrinos, gamma rays -- who knows," says Mathews.

(Marcus Chown)

If you haven't seen this one already it might be a little late, but anyway:

Alan Head (LIE) and Geoff Prince (James Sherring's DIMSYM) will be doing their best to teach participants how to use Australia's best symmetry-finding software. You are invited to bring along your own differential equations and we will help you with the symmetry analysis. The atmosphere will be informal with some brief introductory talks about symmetry analysis, DIMSYM and LIE and then two days of hands-on use with PC's and mainframes. We will wind up with a round table discussion of results. Geoff and Alan will part with many closely guarded secrets so this is your one-off opportunity to become an expert in this ever popular area. Graduate students and researchers alike are welcome.

Accomodation is available at the University's Glenn College at $41 per night bed and breakfast. There will be a registration fee of $25 (to cover our costs) payable prior to the meeting. There is a LIMIT of 12 participants (due to the interactive nature of the event) so get your registration in now:

Name:

Institution:

Email:

Phone:

Fax:

Returning this form (by email) indicates your commitment to attend the workshop. We will confirm your attendance by return email and tell you how to pay your registration fee.

All queries concerning the Workshop should be addressed to Geoff Prince (addresses/phone below).

Geoff Prince Email: G.Prince@latrobe.edu.au Mathematics Phone: +61 3 9479 2601 LaTrobe Univ. Fax: +61 3 9479 3670 Melbourne

gr-qc/9601034 [Source] [Postscript]

Title: The Rotating Quantum Vacuum

Author(s): Paul C. W. Davies , Tevian Dray , Corinne A. Manogue

Comments: Plain TeX, 10 pages (to appear in PRD) Report-no: ADP 95-43/M36 (University of Adelaide)

We derive conditions for rotating particle detectors to respond in a variety of bounded spacetimes and compare the results with the folklore that particle detectors do not respond in the vacuum state appropriate to their motion. Applications involving possible violations of the second law of thermodynamics are briefly addressed.

hep-th/9602100 [Source] [Postscript]

Title: The search for "polarized" instantons in the vacuum

Author(s): M.Yu. Kuchiev (University of New South Wales)

Comments: 16 pages, 2 Postscript figures

The new phase of a gauge theory in which the instantons are "polarized", i.e. have the preferred orientation is discussed. A class of gauge theories with the specific condensates of the scalar fields is considered. In these models there exists an interaction between instantons resulting from one-fermion loop correction. The interaction makes the identical orientation of instantons to be the most probable, permitting one to expect the system to undergo the phase transition into the state with polarized instantons. The existence of this phase is confirmed in the mean-field approximation in which there is the first order phase transition separating the "polarized phase" from the usual non-polarized one. The considered phase can be important for the description of gravity in the framework of the gauge field theory.

gr-qc/9603054 [Source] [Postscript]

Title: Cosmological Time in Quantum Supergravity

Author(s): Robert Graham , Hugh Luckock (Sydney University)

Comments: 12 pages, LaTeX

The version of supergravity formulated by Ogievetsky and Sokatchev is almost identical to the conventional $N=1$ theory, except that the cosmological constant $\Lambda$ appears as a dynamical variable which is constant only by virtue of the field equations. We consider the canonical quantisation of this theory, and show that the wave function evolves with respect to a dynamical variable which can be interpreted as a cosmological time parameter. The square of the modulus of the wave function obeys a set of simple conservation equations and can be interpreted as a probability density functional. The usual problems associated with time in quantum gravity are avoided.

gr-qc/9604022 [Source] [Postscript]

Title: A New Theory of Stochastic Inflation

Author(s): Andrew Matacz (Sydney University)

Comments: 25 pages in latex (uses revtex), no figures.

The stochastic inflation program, first initiated by Starobinsky, is a framework for understanding the dynamics of a quantum scalar field driving an inflationary phase. Though widely used and accepted, there have over recent years been serious criticisms of this theory. In this paper I will present a new theory of stochastic inflation which avoids the problems of the conventional approach. Specifically, the theory can address the quantum-to-classical transition problem, and it will be shown to lead to a dramatic easing of the fine tuning constraints that have plagued inflation theories.

Other GRG related entries at xxx.lanl.gov from Australasia in last few months:

gr-qc/9602016
[Source]
[Postscript]

Title: Modified Relativity from the kappa-deformed Poincare Algebra

Author(s): J.P. Bowes , P.D. Jarvis (Tasmania)

Comments: 11 pages long, to appear in 'Class Q Grav'

Report-no: UTAS-PHYS-95-14

The theory of the $\kappa$-deformed Poincare algebra is applied to the analysis of various phenomena in special relativity, quantum mechanics and field theory. The method relies on the development of series expansions in $\kappa^{-1}$ of the generalised Lorentz transformations, about the special-relativistic limit. Emphasis is placed on the underlying assumptions needed in each part of the discussion, and on in principle limits for the deformation parameter, rather than on rigorous numerical bounds. In the case of the relativistic Doppler effect, and the Michelson-Morley experiment, comparisons with recent experimental tests yield the relatively weak lower bounds on $\kappa c$ of 90eV and 250 keV, respectively. Corrections to the Casimir effect and the Thomas precession are also discussed.

hep-th/9603022 [Source] [Postscript]

Title: Quantum mechanics in multiply connected spaces

Author(s): Vu B Ho , Michael J Morgan (Monash)

Comments: Latex 15 pages

This paper analyses quantum mechanics in multiply connected spaces. It is shown that the multiple connectedness of the configuration space of a physical system can determine the quantum nature of physical observables, such as the angular momentum. In particular, quantum mechanics in compactified Kaluza-Klein spaces is examined. These compactified spaces give rise to an additional angular momentum which can adopt half-integer values and, therefore, may be identified with the intrinsic spin of a quantum particle.